The overall goal of this research program is to understand copper metabolism and its function as a micronutrient. The primary aim of this proposal is to investigate the intracellular distribution of copper in relation to an intracellular copper protein. We propose that the expression of Cu2 Zn2 superoxide dismutase (Cu/Zn-SOD) includes a regulatory step by copper. Although copper does not induce the synthesis of Cu/Zn-SOD messenger RNA, the hypothesis submits that changes in physiological states that require an enhanced level of Cu/Zn-SOD must be accompanied by changes in copper metabolism. Several studies have examined the induction of Cu/Zn-SOD expression and have found no effects under circumstances where it would be important that Cu/Zn-SOD levels be increased. We submit that the reason these studies showed no effect is that the conditions did not include a source of copper for expression of Cu/Zn-SOD activity. We propose that cofactor availability is a critical factor in the regulation of Cu/Zn-SOD and ultimately the ability of the cell to defend itself against free radical damage. To test this hypothesis, we will accomplish the following specific aims: First, we will correlate the steady state levels of intracellular copper with the expression of Cu/Zn-SOD in cultured human cells of promyelocyte origin. Second, we will alter the cellular copper status and determine the effects on Cu/Zn-SOD synthesis and expression of activity. And third, we will alter the expression of Cu/Zn-SOD and determine changes in copper metabolism that must accompany the expression of Cu/Zn-SOD activity. We will examine the synthesis of Cu/Zn-SOD by measuring protein levels, messenger RNA levels and activity levels. The influence of copper availability on these parameters of Cu/ZnSOD and where copper exerts its influence will be determined. We ask if a lack of copper influences the translation or transcription of the protein. We will induce changes in the expression of Cu/Zn-SOD and will examine the influence on copper metabolism. We will determine whether an increased need for copper comes from intracellular stores or must be obtained from external sources. This work is directed at understanding the regulation of both copper metabolism and Cu/Zn - SOD synthesis. It will provide greater knowledge of the function of this trace element during cellular differentiation and in chronic disease.